定义：将光纤中的光功率传输到电子器件中的光纤。

光纤电缆可以将光源中的光功率传输到需要用的地方。电力光纤或者光子电源表示光功率是由激光二极管产生，然后在底端传化成一些电子器件中的电能。
这种转化可以通过光伏电池来得到，即采用砷化镓、铟磷或者铟镓砷等材料制作的半导体器件。
典型的系统包括一个辐射几瓦特光功率的激光二极管，几百米长的多模光纤和有源区为几平方毫米有源区的光电池。 

虽然绝缘铜线传输电能是一种更加简单的方法，但是电力光纤在某些特殊领域具有很大的优势： 

• 不导电的光纤电缆（采用玻璃光纤或者塑料光纤）可以用在高电压的情况下。例如，光纤可以传输高压传输线中电流换能器的功率。
• 这种采用光功率隔离器的电流传感器可以替代体变压器系统。 
• 当器件与天线连接时，电力光纤的绝缘性质也非常有用（例如，一些微波信号接收器），因为有可能会被闪电击中。这时就不存在闪电进入电缆的危险。 
• 采用光学传输可以避免强磁场（例如，磁共振成像）和电磁干扰的影响。并且也不会辐射任何电磁场，因此也不会干扰其它器件。 
• 并且不会存在爆炸材料引起的风险（例如，飞机上的油箱），但是电学器件会产生电火花。 
• 在光纤通信系统中，如果没有电子连接器时可以采用备用光纤传输光。 
• 光纤比电缆重量轻很多，并且可以耐高温。 
• 光纤可以从传感器中传回数据，需要利用其他的波长信道。 

因此，这种光纤有望应用于很多领域，例如工业传感器，航空和光学通信中。 
但是一个很明显的缺点是光学元件的成本和能实现的有限功率和转换效率。当功率为几瓦特时还存在激光安全问题，因为有可能使光纤损坏。 

波长选取和功率效率 
在短距离传输时，辐射750-850 nm附近的激光二极管可以与GaAs光伏电池结合。光伏电池的功率效率很容易达到40-50%，即比普通的太阳能电池高很多，因为光子能量与光伏电池的带隙更加匹配。采用短光纤系统的电电效率可以在20-30%量级。 
光纤中的光学损耗主要来自于散射，限制了传输距离和系统的功率效率。工作在更长波长处的系统可以实现更长的传输距离（几千米），因为拉曼散射显著减小。

Definition: delivery of power for electronic devices via light in an optical fiber

Optical fibers or fiber cables can be used for transmitting optical power from a source to some application. The term power over fiber or photonic power implies that the optical power is generated from electric power – usually with a laser diode – and at the end converted back to electrical power for some electronic device. That conversion can be done with a photovoltaic cell, i.e., a semiconductor device based on a material such as gallium arsenide, indium phosphide, or indium gallium arsenide. A typical system contains

• a laser diode emitting a few watts of optical power,
• a multimode fiber with a length between a couple of meters and a few hundred meters, and
• a photovoltaic cell with an active area of several square millimeters.

For short-range transmission, laser diodes emitting around 750–850 nm are typically used in combination with GaAs-based or silicon-based photovoltaic cells. Long transmission distances (possibly several kilometers) can be realized with systems operating at longer optical wavelengths, because this drastically reduces Rayleigh scattering.

Typical transmitted powers are some hundreds of milliwatts or a few watts, but there is no principal reason why one should not be able to transmit much more, such as dozens or even hundreds of watts, given that multimode fibers with a sufficiently large core can transmit many kilowatts. It is only that the required photovoltaic cells would lead to a very large receiver.

A possible alternative is the light transmission through free space, but that approach is normally less practical, since it involves alignment and a higher risk of interruptions of the beam, and for large transmission distances also limitations due to beam divergence. In addition, there may be problems with laser safety.

Power Efficiency of Power over Fiber

The following sources of power losses need to be considered:

• Efficient laser diodes typically have efficiencies around 50% to 60% including fiber coupling.
• Propagation losses in the fiber (through scattering and absorption) are usually negligible, unless the transmission distance is quite long.
• While photovoltaic cells typically feature efficiencies of only ≈25% when used as solar cells, they can be far more efficient when operated with quasi-monochromatic light: efficiencies well about 50% are easily reachable, even nearly 70% have been demonstrated already, and even somewhat more should be possible. For that, the photon energy of the laser must be somewhat above (but not too far above) the band gap energy.
• Some additional losses may occur in electronics needed to transform the generated voltage to the required level and to stabilize it for the application.

Overall, a power conversion efficiency (electrical-to-electrical) around 20% to 30% should typically be feasible. For low required power levels, such losses should normally be well acceptable, while for higher power levels one will normally try to further optimize the efficiency to 40% or higher.

Advantages of Power over Fiber

Although an insulated copper wire is a simpler technology for transferring electric power, power over fiber offers advantages in specific situations:

• Non-conducting fiber cables (based on glass fibers or plastics) can be installed where high electric voltages occur. For example, a fiber can transmit power for a current transducer in a high-voltage transmission line. (Note that there are also fiber-optic sensors where no electrical power is needed locally.) Such current sensors with an optical power isolator can replace bulky transformer systems.
• The insulating property is also useful when a device (e.g. some radio signal receiver) is connected to an antenna, which could be hit by lightnings. There is then no risk that lightning strokes are transmitted via the cable.
• Optical delivery of power avoids any sensitivity to strong magnetic fields (e.g. in magnetic resonance imaging) and to electromagnetic interference. Conversely, no electromagnetic radiation, which might disturb other devices, can be emitted, and also no DC magnetic fields are generated.
• There is no risk that explosive materials (e.g. in a fuel tank of an airplane) can be ignited, as could occur e.g. via an electric spark.
• In a system for optical fiber communications, there may be spare fibers which can be used for transmitting power when an electrical connection does not exist. Other possibilities are to use some separate fiber core(s) of a multi-core fiber, or even to use one fiber core for both power delivery and data transmission.
• A fiber can have a far lower weight than an electrical cable, and may also be thinner.
• The same fiber may be used to send back data e.g. from a sensor, using some other wavelength channel.

Therefore, a number of applications can be envisaged in areas such as industrial sensors, aerospace, and optical communications.

Obvious disadvantages are the cost of optical components and the limited potential in terms of available power and conversion efficiency. There may also be a laser safety issue associated with several watts of optical power, which can leave the fiber when it is broken.

Laser Safety

During normal operation, the laser light is fully confined in the fiber, and there is no risk e.g. for nearby persons. However, a substantial laser safety issue may arise when the fiber is broken, so that the laser light can exit. Despite the substantial divergence, a few watts of near-infrared light need to be considered as fairly dangerous for human eyes. Therefore, one may need to use a well protected fiber cable, or possibly include additional features for automatically switching off the laser when a fault is recognized.